A lesion located at or near a bifurcation in a vessel, such as at the ostium of a side branch which extends from a main branch or in the main branch at a bifurcation, may be treated using a balloon catheter or a catheter with a stent. However, treatment of such lesions is a challenge. If a balloon is used to treat an ostial lesion of a side branch, the atherosclerotic plaque may be displaced by the balloon dilatation or by stent or scaffold implantation towards the main branch, thereby creating a new obstruction by “plaque shift.” In particular this complication is likely to occur when the lesion is located at the carina, that is, the distal branchpoint of the two vessels forming the bifurcation.
In order to avoid this complication, a technique known as the “kissing balloon” technique is often used, wherein simultaneous dilatation of the main branch and the side branch is performed. In this technique, two balloons are introduced separately into each of the vessel and are simultaneously inflated. However, this results in two inflated balloons lying parallel to each other in the main branch, creating a non-circular dilatation body in the main branch, potentially resulting in vessel trauma and non-homogenously distributed dilatation forces upon the vessel wall. Moreover, if a stent or scaffold has already been placed in the main branch, the kissing balloon technique with two balloons lying over a particular length parallel to each other within the stent or scaffold results in distortion of the stent or scaffold due to the non-circular dilatation body and partial separation of the stent from the vessel wall. This is known to carry the risk of early and late complications such as vessel thrombosis, restenosis or occlusion and interruption of homogenous drug elution from the stent to the vessel wall in the case of drug eluting stents.
Similarly, when a stent or stents or scaffolds are used, overlapping of stents or protrusion of a stent from the ostium of a side branch into the main branch may also result in vessel trauma or unwanted plaque shifts, or may result in flow obstruction, thrombosis formation, and potentially distortion or crushing of stent materials if a balloon dilatation in the main branch is performed or if a second stent is later introduced in the main branch bridging the side branch ostium.
U.S. patent application Ser. No. 13/826,399 to Ischinger, which has been published as US Patent Publication Number 2014/0277,377A1, discloses an oblique stent which is designed to more closely fit the bifurcation anatomy, thus minimizing the protrusion of a portion of the stent material from the side branch into the main branch or vice versa. With the use of an oblique shaped stent, less metal protrusion and distortion occurs, but the problems of plaque shift and/or main vessel compromise may still exist.
U.S. Pat. No. 6,682,556 to Ischinger discloses a balloon catheter for more precise placement of an oblique stent into a side branch. However, the balloon catheter disclosed therein includes a conventional angioplasty balloon, which in its inflated state has a body section and further includes a proximal section and a distal section, both of which exhibit a symmetrical cone shape. The cone shape of the two end-sections includes the balloon tip, and symmetrical balloon shoulders which merge into the balloon body.
Thus, a balloon specifically shaped to better match the bifurcational anatomy and/or the shape of an oblique stent or scaffold would result in more successful bifurcation treatment, including less traumatic and less harmful kissing balloon techniques.
There is thus a need for a torquable balloon which better suits the bifurcational anatomy and permits conventional stent or scaffold and oblique stent or oblique scaffold deployment in a side branch ostium or in a diseased vessel bifurcation and further provides balloon dilatation of an ostial lesion or a vessel bifurcation, without obstructing flow in the main branch or leading to stent or scaffold material distortion and permitting kissing balloon techniques minimizing their current risks.